Minor Change Existing Approval - OPW24 0125 01 (As Published) · OPW24/0125.01

                      Stormwater Drainage
               33.    Appropriate scour protection must be provided at the outlet of all stormwater pipes including
                      temporary outlets.
               34.    Works associated with this permit must not adversely impact on the existing drainage
                      conditions on other properties (e.g., by blocking or interfering with natural overland flows).
               35.    Construction of all internal stormwater drainage works must comply with the relevant
                      section/s of Australian Standard AS/NZS 3500.3.
                      Erosion and Sediment Control
               36.    Prescribed Water Contaminants (as defined in Schedule 10 of Environmental Protection
                      Regulation 2019) must not be released from the site or to waters within the site, or be likely
                      to be released should rainfall occur, unless all reasonable and practicable measures are
                      taken to prevent or minimise the release and concentration of contamination. These
                      measures must be designed, implemented and maintained in accordance with “Best Practice
                      Erosion and Sediment Control” published by the International Erosion Control Association
                      (Australasian Chapter) (IECA, 2008), to the extent that such measures and practices are also
                      consistent with the following:
                      a.      minimise erosion:
                              iii.     for areas of the site which drain to a sediment basin, implement drainage and
                                       erosion control measures prior to rainfall which prevent or minimise rill erosion
                                       and gully erosion
                              iv.      For areas of the site which do not drain to a sediment basin, implement drainage
                                       and erosion control measures prior to rainfall (including contingency measures)
                                       which prevent or minimise erosion, including rain drop erosion, chemical erosion,
                                       rill erosion and gully erosion
                      b.      manage concentrated stormwater flows:
                              i.       prior to each rainfall event ensure concentrated stormwater flow paths are
                                       provided with capacity in accordance with IECA (2008) Table 4.3.1 and are
                                       structurally stable in all rainfall events for the following sources:
                                       a)   from stormwater catchments upslope of the area of disturbance which are
                                            either stable or external to the site, ensure stormwater is diverted or
                                            managed either:
                                            i.    around the site or through the site without causing erosion and
                                                  without contaminating the flow; or
                                            ii    if it is impractical to convey the flows around or through the site,
                                                  convey the flows into appropriately sized sediment basins without
                                                  causing erosion.
                                       b)   from all disturbed areas of the site to sediment basin(s) without causing
                                            erosion
                      c.      minimise sediment released from the site:
                              i.       prior to each rainfall event ensure concentrated stormwater flow paths are
                                       provided with capacity in accordance with IECA (2008) Table 4.3.1 and are
                                       structurally stable in all rainfall events for the following sources:
                                       a)   each basin is sized and operated in accordance with either a Type-A or
                                            Type-B sediment basin as documented in IECA (2008) Appendix B (June
                                            2018).
                                       b)   each basin is to be provided with an automated system of flocculent dosing
                                            and a suitable supply of flocculent/coagulant, with the type of
                                            flocculent/coagulant determined based on Chemical Coagulants and
                                            Flocculants Fact Sheet (IECA, 2018).


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Document Set ID: 23995807
Version: 4, Version Date: 05/08/2025